Obtaining MCI System Information

The sysinfo (MCI_SYSINFO) command obtains system information about MCI devices. MCI handles this
command without relaying it to any MCI device. For the command-message interface,
MCI returns the system information in the MCI_SYSINFO_PARMS structure.

You can use the sysinfo (MCI_SYSINFO) command to retrieve information such as the number of MCI devices on a
system, the number of MCI devices of a particular type, the number of open MCI
devices, and the names of the devices. This command is often called more than once
to retrieve a particular piece of information. For example, you might retrieve
the number of devices of a particular type in the first call and then enumerate
the names of the devices in the next.